1. Status of measurements with the Napoli TPC
C. Altucci, S. Amoruso, M. Armenante, R. Bruzzese, F. Carbonara, A. Cocco, M. Della Pietra, A. Di Cicco, A. Ereditato, G. Fiorillo, V. Gallo, A. Maurano, B. Rossi, R. Santorelli, N. Spinelli, R. Velotta, X. Wang
Special thanks to many ICARUS colleagues for support and suggestions:
Pavia for the UV laser source
Padova for the R/O electronics and the TPC design
LNGS for the TPC construction
B. Rossi - LNGS June 2005
ICARUS Meeting

2. Content Description of the TPC
Firsts events detected with theTPC prototype: cosmic events and laser tracks
Laser data analysis
Measurement of ionization vs laser energy
Results and next goals
B. Rossi - LNGS June 2005
ICARUS Meeting

3. Napoli setup
B. Rossi - LNGS June 2005
ICARUS Meeting

4. Napoli Laboratory Electronic Rack Mirror Oxysorb filter Flange
HV cable
Mirror
Oxysorb filter
Flange
Signal cable
Twisted-pair
Fill in
Dewar
GAr Cooling
system cable
Dewar
B. Rossi - LNGS June 2005
ICARUS Meeting

5. HV feedthrough Vacuum system Pressure meter Valve Membrane pump
“I” variable
connector
Pressure
meter
HV feedthrough
Vacuum system
Valve
Membrane
pump
B. Rossi - LNGS June 2005
ICARUS Meeting

6. Criogenic lines with external tanks
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ICARUS Meeting

7. B. Rossi - LNGS June 2005
ICARUS Meeting

8. 2nd floor for recirculation system
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ICARUS Meeting

9. Recirculation system dewar
E-valve
GAr in
Safey valve
LAr in
Dewar
B. Rossi - LNGS June 2005
ICARUS Meeting

10. B. Rossi - LNGS - 27-28 June 2005 ICARUS Meeting HV Welding Screw
Connection with HV
B. Rossi - LNGS June 2005
ICARUS Meeting

11. TPC and Electric fields
Cathode
TPC and Electric fields
Vetronite
Flange HV
feedthrough
Race tracks
Level meter
Signal
cables
Electric fields to have two induction planes
con
Vertical
frame
r=wire radius (75mm), p=pitch (3mm)
E1 = 500V/cm
E2 = 750V/cm
E3 = 1125V/cm
Wire plane Shield = 98%
Trasparency = 87%
Orizonthal
frame
Mirrors
B. Rossi - LNGS June 2005
ICARUS Meeting

12. B. Rossi - LNGS June 2005
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13. B. Rossi - LNGS June 2005
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14. B. Rossi - LNGS June 2005
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15. B. Rossi - LNGS June 2005
ICARUS Meeting

16. TPC configuration E1= 500 V/cm - - - - - - - - - - + + + + + 30 cm
Two anodic wire planes (Ind1 & Ind2). 96 wires per plane.
Ind2 is parallel to the laser beam ionization.
Ind1 output is a signal only from a few number (<4)
of wires positioned in the center of the plane.
Mid wire is #48.
Ind1 is orthogonal to the laser beam ionization.
Its output must be the same signal at the
same time from all 96 wires of the plane
E3= 1125 V/cm
Anode: – 1063 V
Ind 2: – 725 V
E2= 750 V/cm
Ind 1: – 500 V
@275 samples
30 cm
13 cm - - - - - - - - - - + + + + +
17 cm
E1= 500 V/cm
1 cm = 25 samples
Cathode: – V
B. Rossi - LNGS June 2005
ICARUS Meeting

17. Cosmic event gallery
B. Rossi - LNGS June 2005
ICARUS Meeting

18. Cosmic track B. Rossi - LNGS - 27-28 June 2005 ICARUS Meeting Setting
Npre = 200
Run 550 Event june 2005 h. 16: E.F. = 500 V/m Vdrift=1.56mm/ms Sample = 400 ns
Induction 1 wiev
Induction 2 wiev
ID wire
ID wire
125
125
100
100 75 75 50 50 25 25
Drift time (Samples=400ns)
Drift time (Samples=400ns)
B. Rossi - LNGS June 2005
ICARUS Meeting

19. Cosmic track Detected with LTCU trigger
Run 550 Event june 2005 h. 18: E.F. = 500 V/m Vdrift=1.56mm/ms Sample = 400 ns
ID wire
ID wire
Induction 1 wiev
Induction 2 wiev
100
100
Detected with
LTCU trigger 75 75 50 50 25 25
Drift time
(Samples=400ns)
Drift time
(Samples=400ns)
Wire 80
Wire 45
ADC count
(mV)
ADC count
(mV)
B. Rossi - LNGS June 2005
ICARUS Meeting

20. Cosmic track B. Rossi - LNGS - 27-28 June 2005 ICARUS Meeting Wire 70
Run 550 Event june h. 18: E.F. = 500 V/m Vdrift=1.56mm/ms Sample = 400 ns
ID wire
ID wire
Induction 1 wiev
Induction 2 wiev
100
100 75 75 50 50 25 25
Drift time
(Samples=400ns)
Drift time
(Samples=400ns)
Wire 70
Wire 44
Wire 45
ADC count
(mV)
ADC count
(mV)
B. Rossi - LNGS June 2005
ICARUS Meeting

21. Cosmic track B. Rossi - LNGS - 27-28 June 2005 ICARUS Meeting Wire 72
Run 550 Event june 2005 h. 18: E.F. = 500 V/m Vdrift=1.56mm/ms Sample = 400 ns
ID wire
ID wire
Induction 1 wiev
Induction 2 wiev
100
100 75 75 50 50 25 25
Drift time
(Samples=400ns)
Drift time
(Samples=400ns)
Wire 72
Wire 59
Wire 45
ADC count
(mV)
ADC count
(mV)
B. Rossi - LNGS June 2005
ICARUS Meeting

22. Cosmic track B. Rossi - LNGS - 27-28 June 2005 ICARUS Meeting Wire 43
Run 550 Event april 2005 h. 18: E.F. = 500 V/m Vdrift=1.56mm/ms Sample = 400 ns
ID wire
ID wire
Induction 1 wiev
Induction 2 wiev
100
100 75 75 50 50 25 25
Drift time
(Samples=400ns)
Drift time
(Samples=400ns)
Wire 43
Wire 62
ADC count
(mV)
ADC count
(mV)
B. Rossi - LNGS June 2005
ICARUS Meeting

23. Shower B. Rossi - LNGS - 27-28 June 2005 ICARUS Meeting Wire 45 Wire
Run 550 Event june 2005 h. 18: E.F. = 500 V/m Vdrift=1.56mm/ms Sample = 400 ns
ID wire
ID wire
Induction 1 wiev
Induction 2 wiev
100
100 75 75 50 50 25 25
Drift time
(Samples=400ns)
Drift time
(Samples=400ns)
Wire 45
Wire 92
ADC count
(mV)
ADC count
(mV)
B. Rossi - LNGS June 2005
ICARUS Meeting

24. Shower B. Rossi - LNGS - 27-28 June 2005 ICARUS Meeting Wire 43
Run 550 Event june 2005 h. 18: E.F. = 500 V/m Vdrift=1.56mm/ms Sample = 400 ns
ID wire
ID wire
Induction 1 wiev
Induction 2 wiev
100
100 75 75 50 50 25 25
Drift time
(Samples=400ns)
Drift time
(Samples=400ns)
Wire 43
Wire 50
ADC count
(mV)
ADC count
(mV)
B. Rossi - LNGS June 2005
ICARUS Meeting

25. UV-LASER DAQ
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26. Laser DAQ trigger
The Trigger pulse is the output signal of the lasers’ photodiode (in this case > 5V).
This pulse is converted to a NIM signal and then is sent to the DAQ rack.
The DAQ rate is 1 Hz.
Daedalus setting
Npre = 200
13 cm of drift
At 1.3mm/ms
Are 270 samples
We wait the track
At sample
ADC Buffer
NIM signal
e- drift
Trigger pulse
-800 mV
100 ns
200
475
samples
1024
128 ms
410 ms
B. Rossi - LNGS June 2005
ICARUS Meeting

27. Laser event Npre = 200 Wire #1 is the sample in which arrives
Run 467 Event june 2005 h. 18: E.F. = (500/750/1100)V/cm Vdrift=1.34mm/ms Sample = 400 ns
ID wire
ID wire
Induction 1 wiev
Induction 2 wiev
100
Npre = 200
is the sample in
which arrives
the trigger signal
100
150 mm 75 75 50
320 mm 50
Wire #1
Is the nearest
To the laser beam
input 25 25
Drift time
(Samples=400ns)
Drift time
(Samples=400ns)
ADC
count
(mV)
ADC
count
(mV)
Wire 38
Wire 48
B. Rossi - LNGS June 2005
ICARUS Meeting

28. Laser event B. Rossi - LNGS - 27-28 June 2005 ICARUS Meeting Wire 48
Run 467 Event april 2005 h. 18: E.F. = 500 V/m Vdrift=1.34mm/ms Sample = 400 ns
Induction 1 wiev
Induction 2 wiev
ID wire
ID wire
100
100 75 75 50 50 25 25
Drift time
(Samples=400ns)
Drift time
(Samples=400ns)
ADC
count
(mV)
ADC
count
(mV)
Wire 48
Wire 25
B. Rossi - LNGS June 2005
ICARUS Meeting

29. Laser event B. Rossi - LNGS - 27-28 June 2005 ICARUS Meeting Wire 48
Run 467 Event april 2005 h. 18: E.F. = 500 V/m Vdrift=1.56mm/ms Sample = 400 ns
Induction 1 wiev
Induction 2 wiev
ID wire
ID wire
100
100
The induction 1 signal
is too big and Induces
a signal on the
Other plane 75 75 50 50 25 25
Drift time
(Samples=400ns)
Drift time
(Samples=400ns)
ADC
count
(mV)
ADC
count
(mV)
Wire 48
Wire 24
B. Rossi - LNGS June 2005
ICARUS Meeting

30. Laser event B. Rossi - LNGS - 27-28 June 2005 ICARUS Meeting Wire 48
Run 467 Event april 2005 h. 18: E.F. = 500 V/m Vdrift=1.56mm/ms Sample = 400 ns
Induction 1 wiev
Induction 2 wiev
ID wire
ID wire
100
100 75 75 50 50 25 25
Drift time
(Samples=400ns)
Drift time
(Samples=400ns)
ADC
count
(mV)
ADC
count
(mV)
Wire 48
Wire 25
B. Rossi - LNGS June 2005
ICARUS Meeting

31. LAr IONIZATION MEASUREMENT B. Rossi - LNGS - 27-28 June 2005
ICARUS Meeting

32. Liquid phase produces a shift of the energetic levels
Liquid ionization potential is lower than the gaseous one due to three effects:
the gain of a polarization energy for a positive ion immersed in a liquid (Born’s formula)
Broadening of the energetic levels for the creation of different valence levels (that is due to the condensation but is negligible for not polar molecules)
Lowering of the conductions levels
Can be measured with the variation of the threshold of the photoelectric effect observed at the solid-liquid interface
Born’s formula
Fl extraction potenzial in liquid
For Argon
R = 0.88Å
r = 1.5
Fv extraction potenzial in vacuum
V0 energetic shift of the liquid phase
Ar  V0=-0.2 eV
P+ = eV
B. Rossi - LNGS June 2005
ICARUS Meeting

33. Stark shift and broadening  0.62 eV resonance
This two effects lead a reduction of LAr ionization potential of
Eval molto piccola per
interazioni Van der Vaals
DE=P++V0+Eval-1.76 eV
We believe that this can be a three photon process
Stark shift and broadening  0.62 eV
resonance
B. Rossi - LNGS June 2005
ICARUS Meeting

34. Their model leads to a Cross section 10 order
Sun et al. results
Their model leads to a Cross section 10 order
bigger than a normal
2 photon process
There’s a close relaction between the slope of the fit data and the order of the process
Classical formula
B. Rossi - LNGS June 2005
ICARUS Meeting

35. Our preliminary measurements
To have a rough estimate of the LAr ionization yield and a quick analisys we have only considered the signal induced by the the laser beam on the second TPC wire plane.
Every laser source has an instability in energy. In our case the instability is about 5% (data sheet)
To solve this problem
We’ve used a photodiode to have a relative measurement of the single spot laser energy.
The laser beam induces a signal usually on one wire (<3) because it is parallel to the light beam
The photodiode needs a calibration since one measures only a few % of the single spot laser energy.
E.F. = (+500/+750/-500)V/cm
With this E.F. we have that
All the electrons are collected on the second wire plane
B. Rossi - LNGS June 2005
ICARUS Meeting

36. Photodiode calibration
Photodiode Output
We’ve measured the peak output of
the photodiode by varying the laser
energy in the range mJ
and measuring this energy with a
digital Joulemeter
Joule meter
Sensor
PRISM
B. Rossi - LNGS June 2005
ICARUS Meeting

37. Photodiode output (mV)
Photodiode calibration
Photodiode output (mV)
Y= x
Energy (mJ)
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ICARUS Meeting

38. Energy (u.a.) Photodiode output (mJ)
LAr ionization vs laser energy
Power of 3
3 g process
Area (a.u.)
Y= x3.0
Very Preliminary
B. Rossi - LNGS June 2005
Energy (u.a.) Photodiode output (mJ)
ICARUS Meeting

39. Summary Results: Next goals:
cosmic events detected with the LTCU trigger
UV-laser induced tracks measured
Preliminary results on ionization yield vs laser Energy
Next goals:
improve data taking (noise) conditions
compare our (near future) results with those of Sun et al.
study the ionization process in a wider energy range
data analysis of the ind1 laser tracks
measurement of the cross section of the ionization process
B. Rossi - LNGS June 2005
ICARUS Meeting